The invention relates to a separator for liquids, particularly for purifying crankcase gases by removing entrained oil droplets therefrom. The invention further relates to a separating cartridge that is suitable for installation in the aforementioned liquid separator.
An oil separator using a replaceable separating cartridge is known, for example, from published German patent application no. DE 196 45 666 A1. The separating cartridge is installed in a housing in such a way that a seal is formed between a treated gas zone and an untreated gas zone, i.e., between the oil-containing air and the nearly oil-free air, so that the gas stream to be purified must flow through a separating area of the separating cartridge. The separated liquid can exit the housing through an outlet.
The separating cartridge can be replaced when the dirt contained in the gas stream has clogged the separating material of the cartridge and the pressure drop produced by the cartridge increases to an excessive level. Since the separating cartridge is a replaceable part, the economic efficiency of the liquid separator essentially depends on the cost of the replacement cartridges. The separating cartridge proposed in the aforementioned document therefore has a simple construction. It comprises a cup-shaped support around which the separating material is wound. This simple construction has drawbacks, however. The winding of the separating material on the support can result in leaks along the edge areas at the end faces. Furthermore, the separating cartridge or the associated retainer in the housing of the liquid separator must be provided with seals to ensure proper functioning of the component. This reduces the economic efficiency that the simple construction of the separating cartridge is intended to provide. Besides, concessions must be made regarding the functional reliability of the separating cartridge.
U.S. Pat. No. 4,082,071 discloses an oil separator in which a flaccid nonwoven fabric is wound around a support body. End plates are subsequently joined to the support body and the nonwoven fabric on the end faces. These end plates simultaneously ensure a tight installation in the associated housing. The construction of this oil separating element is rather complex, however, so that the replacement part is expensive to produce. As a result, the oil separator is costly to maintain.
On the other hand, German patent no. DE 42 41 586 discloses an air filter element in which the filter element needs no support tube. The supporting mechanism is instead incorporated into the housing so that it does not need to be replaced each time the filter cartridge is replaced. This permits a cost-effective production of the filter element. However, an oil separator of this type cannot be removed due to the generally flaccid components that are being used as the filter medium. These components require direct support, so that a filter element with a nonwoven fabric could not be pushed onto a support body that is permanently installed in the filter housing.
Thus, it is an object of the invention to provide a liquid separator which uses a simply constructed separating cartridge that is cost-effective to produce and at the same time ensures high component reliability. It is also an object of the invention to provide a simply constructed, cost effective and highly reliable separating cartridge for use in a liquid separator.
In accordance with a first aspect of the invention, the objects are achieved by providing a liquid separator for separating liquid entrained in a gas flow, the separator comprising a housing with a cover having an inlet and an outlet for a gas to be purified and a drain for separated liquid; a mount for a separating cartridge; and a substantially cylindrical separating cartridge received on the mount; wherein the separating cartridge comprises a separating means wound around a support member with end disks on both axial end faces thereof; wherein the end disks engage the mount to form a seal and together with the support member form a sealed assembly which divides the separator into an untreated gas zone and a treated gas zone, and wherein the mount is constructed as a nipple that is gas permeable in the area between the end disks of the separating cartridge.
In another aspect of the invention, the objects are achieved by providing a substantially cylindrical separating cartridge comprising a separating means wound around a support member with end disks on both axial end faces thereof; wherein the end disks together with the support member are engagable with a mount to form a sealed assembly which divides a liquid separator into an untreated gas zone and a treated gas zone.
The liquid separator according to the invention has a housing that can be sealed in known manner by a cover. Appropriate connections are provided to permit the passage of the gas to be purified and the drainage of the separated liquid. The liquid separator uses a separating cartridge having separating means to separate the liquid and support member to ensure the shape stability of the cartridge. According to the invention, the separating cartridge is constructed in such a way that it has an end disk on at least one of its end faces, which engages or interacts with an associated mount in the housing to form a seal. The end disks may also be fixedly attached to the supporting member, in which case a seal is created between the end disk and the supporting member. This eliminates the need for separate gaskets or seals for installing the cartridge in the housing. The reduction in number of necessary individual components reduces component and assembly costs, not least of all due to material savings. This is also an additional safety factor since it prevents assembly errors when the separating cartridge is being replaced, e.g., the inadvertent omission of a seal. Furthermore, the end disks advantageously lead to a reliable sealing of the separating means. Any undesirable short circuit flow of the gas stream to be purified can thus be counteracted.
All types of known separating materials may be used for the separating means. Particularly suitable are materials that can be wound around the preferably tubular supporting member. In addition to nonwoven separating materials, the separating means may, in particular, comprise a yarn winding.
The primary task of the separating means is to separate a liquid phase from the gas phase. This liquid phase is collected and discharged from the separating arrangement with the aid of a drain. However, the separating means also serve to retain particles contained in the gas to be purified. These particles remain in the separating means and consequently determine the service life of the separating cartridge. To extend this service life, an additional separating stage that is suitable primarily for separating particles may be provided. The separation of the fluid may also be done in several stages. In particular, the supporting member can assume an additional separation function. The supporting member may, for instance, be made from a porous material to separate ultrafine droplets of liquid from the gas phase.
According to a further embodiment of the invention, the separating cartridge is free from metal. This has substantial advantages for the disposal of used separating cartridges since they can be incinerated in a waste-to-energy system.
There are several variants for the further embodiment of the end disks. These variants may also be combined. The separating means as well as the supporting member can, for instance, be embedded in an end disk made of nitrile-butadiene rubber. This material expands with heat during production of the cartridge and thereby encloses the end face areas of the separating means and the supporting member. This bond simultaneously creates the required seal.
Another option is to produce the end disks from a multicomponent synthetic resin material or plastic. It is possible to use foams, which expand similarly to an end disk made of nitrile-butadiene rubber and thereby produce the connection to the separating means and the supporting member. Another possibility is to provide the end face areas of the separating means and/or the supporting member with a preferably liquid component and to contact it with another, preferably more solid, component so that the end disk cures with a certain residual elasticity. Another option is to use elastic end disks that are joined to the end faces of the separating means and the supporting member, e.g., by gluing.
Alternatively, the end disks may also be produced together with the supporting member as a single part. This creates a basic body that is comparable to the structure of a yarn reel. The separating means can then be wound around this basic body.
A seal of the assembly comprising the end disk, supporting member and separating means may also be achieved by compressing them in this area. Compression of the separating means can be accomplished by various means, e.g., by a cable tie, which is slung around the separating means and drawn tight. Instead of using a cable tie, a thread may be incorporated into the nonwoven fabric.
The supporting member itself must be gas permeable. The cylindrical separating cartridges have two end faces, and it is advantageous to provide both end faces with the same type of end disks. Depending on the application, however, another design may also be selected.
The mount provided inside the housing of the liquid separator for the separating cartridge is advantageously provided with locking devices suitable to fix the separating cartridge in installed position. These devices may, for instance, consist of locking projections that are attached to a cylindrical fitting. The separating cartridge is then pushed onto this fitting until the locking projections engage underneath one of the end disks. Other fixation options are also feasible, however. For instance, the surface pressure which is created by the intrinsic elasticity of the end disks and which produces the sealing effect can be simultaneously used as a friction lock between the retainer and the separating cartridge. Another option would be a bayonet catch.
If the retainer for the separating cartridge is constructed in the form of a nipple, it must be gas permeable in the area between the end disks of the separating cartridge in order to allow the gas to be purified to pass through it. The nipple can also assume certain separating functions. This is possible, in particular, if the gas to be purified is guided from the inside toward the outside. The gas then first passes through the nipple, so that a preliminary separation of the fluid can occur, and then passes through the separating material of the separating cartridge.
According to one advantageous embodiment of the inventive concept, the fitting can be provided with a return flow valve for the separated liquid. While the separator is in operation, the return flow valve is closed to prevent unpurified gas from bypassing the separator. If the oil separator stops operating or if a certain amount of separated fluid has collected, then the return flow valve opens so that the separated fluid can be discharged from the nipple.
The fitting advantageously forms a single part together with the cover of the housing. To facilitate molding of the individual parts, they can be produced separately and subsequently permanently connected, particularly by welding. The advantage of the one-piece construction is that it saves a seal.
A separating cartridge in accordance with the invention is characterized in that it is suitable for installation in a liquid separator according to the invention. Alternatively, however, this separating cartridge can also be used without a housing at installation sites where a liquid must be separated from a gas phase in a closed system. This is required, for instance, in the oil system of an internal combustion engine. The crankcase gases that are produced must be guided out of the system and the oil must be removed from them as completely as possible. The liquid separator may be inserted directly into the crankcase housing. For this purpose, a combination of cover and fitting in accordance with the invention may be used. The separating cartridge can also be integrated into an oil filter module.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.